Two-cycle engine



Feb. 24, 1931. L. 11 CLAIR 1,793,975

TWO-CYCLE ENGINE Filed Nov. 22, 1928 2 Sheets-Sheet 1 WWW) law; 6% Czazr $.WM

Feb. 24, 1931. L. ST. CLAIR 1,793,975

TWOCYCLE ENGINE Filed Nov. 22, 1928 2 Sheets-Sheet 2 Mn/Wazoo 76V; 6 503 7 3460 M Patented Feb. 24, 1931 UNITED STATES PATENT OFFICE LEVI ST. CLAIR, OF BERLIN,

NEW HAMPSHIRE, ASSIGNOR OF ONE-THIRD EACH T OVIDE .T. GOULOMBE AND THEODORE MORIN, BOTH 0F BERLIN, NEW HAMPSHIRE TWO-CYpLE ENGINE Applicationfiled November 22,1928. Serial No. 321,131.

The invention relates to improvements in internal combustion engines and has reference more particularly to those of the twocycle type, and it is the object of said invention to provide a new and improved engine of this form in which a separate pump cylinder and pump piston are employed for supplying gas to the power cylinder and in which exceptionally simple yet efficient means are provided for operating the pump piston synchronously with the power piston.

With the foregoing in view, the invention resides in the novel suject matter hereinafter described and claimed, description being accomplished by reference to the accompanying drawing.

Fig. 1 is a vertical sectional view cut transversely of the crank shaft. I

Fig. 2 is a vertical sectional View on line 22 of Fig. 1.

Fig. 3 is a perspective view of the connecting rod between the power piston and the crank shaft.

Fig. 4 is a perspective view of the rocker which forms part of the operating means for the pump piston.

The drawings above briefly described illustrate the preferred form of construction and while this construction is herein specifically explained, it is to, be understood that within the scope of the invention as claimed, variations may be made.

The numeral 5 denotes a crank case through which the crank shaft 6 passes and to which the usual air or water-cooled power cylinder 7 is secured. The crank case 5 is provided with a lateral offset 8 to which a pump cylinder 9 is fastened in parallel relation with the cylinder 7, said pump cylinder being provided with a gas inlet 10 connected with any desired carbureter (not shown), and with a gas outlet 11. This gas outlet opens into the power cylinder 7 in substantially opposed relation with the exhaust 12 from said cylinder, both the inlet and exhaust being controlled in the usual way by the power piston 13 which is of the conventional type for two-cycle engines; A pump piston 14 is within the pump cylinder 9 and the two pistons 13-14 and the crank shaft 6 are connected in a unique manner for movement in synchronism, so that at the completion of each power stroke of the piston 13, the pump piston 14 recharges the cylinder 7, the incoming gas under pressure taking the place of the spent gas which escapes through the exhaust 12..

A connecting rod 15 of unique form connects the piston 13 with the crank shaft 6, the outer end of this connecting rod being provided with a bearing 16 for the usual wrist pin 17 or with a clamp for this pin if the latter turn within bearings of the piston. The inner end of the rod 15 is provided with an appropriate bearing 18 for the shaft crank and said rod is formed with a longitudinal slot 19 extending from a point near the bearing 16 to a point near the bearing 18. Near the outer end of this slot, the side portions of the connecting rod 15 are formed with alined openings 20 which receive an auxiliary wrist pin 21. This pin connects the outer end of a link or auxiliary connecting rod 22 with the rod 15, the slot 19 serving to receive said link during the operation of the engine. The inner end of link 22 is pivoted at 23 to a rocker 24 which is fulcrumed between its ends at 25 in the crank case 5, the ends of said rocker being near the inner ends of the cylinders 7-9 respectively. Both ends of rocker 24 are preferably bifurcated as shown and the end carrying the pivot23 is receivable in the slot 19, the inner end of the latter being preferably enlarged somewhat for this purpose. The other end of rocker 24 is pivoted at 26 to the inner end of a link 27 whose outer end is connected by a wrist pin or other pivot 28 with the pump piston 14.

It will be seen from the foregoing that a simple and compact arrangement of parts has been provided for insuring synchronized movement of the pistons 13-14. and for mov- ,ing them in opposite directions. Each time piston 13 compresses a charge in the power cylinder 7, piston 14 recedes and draws a fresh supply of gas into the cylinder 9 through the intake 10. Then, while expansion is taking place in the cylinder 7 and piston 13 is on its power stroke, piston 1 1 is compressing gas in the pump cylinder 9, and as soon as said pisfor swinging into and out of said slot, a rockerton 13 uncovers the passage 11 and the exhaust passage 12, exhaust gases escape from the cylinder 7 and the fresh charge of gas enters said cylinder through said passage 11. The entire structure is' of extreme simplicity and requires no valve means except the pistons. Moreover, no timing equipment is nec essary except that commonly used in connection with the ignition system for advancing and retarding the spark.

On account of the excellent results obtainable from the general construction shown, it is preferably followed. However, within the scope of the invention as claimed, minor variations maybe made.

I claim 2-- 1. In a two-cycle engine, a power cylinder and a power piston therein, a pump cylinder and a pump piston therein, a gas inlet into the pump cylinder, a gas outlet from this cylinder into the power cylinder and an exhaust from the latter, a crank shaft, a connecting rod of rigid nature throughout its length and having the usual wrist pin and bearing connecting it with said power piston and said crank shaft respectively, a rocker fulcrumed between its ends and having said ends disposed near the inner ends of said cylinders, a link connecting said pump piston with one end of said rocker, and a second link extending longitudinally of said connecting rod, one end of said second link being pivoted to said rocker, the other end of said second link being pivoted to said connecting rod near said wrist pin.

2. In a two-cycle engine, a power cylinder and a power piston therein, a pump cylinder and a pump piston therein, a gas inlet into the pump cylinder, a gas outlet from this cylinder into the power cylinder and an exhaust from the latter, a crank shaft, a connecting rod of rigid nature throughout its length and connected with said power piston and said crank shaft, said connecting rod having a longitudinal slot from a point near said power piston to a point near said crank shaft, a link disposed longitudinally of said slot and pivoted at its outer end to said connecting rod fulcrumed' between its ends and having one of said ends pivoted to the inner end of said link, and a link connecting the other end of said rocker with said pump piston.

3. In an internal combustion engine, a connecting rod having a wrist pin opening at one end and a crank bearing at its other end, said rod having a longitudinal slot from a point near said opening to a point near said hearing and having additional wrist pin openings near the outer end of said slot.

4. A two-cycle internal combustion engine comprising a crank case, a power cylinder secured to said crank case and'ha-ving an intake port and an exhaust port both located between its ends, the inner end of said cylinder being in communication with said crank case, a power piston in said cylinder 'alone acting as valve means for said ports, a pump cylinder secured to and communicating with said crank case, said pump cylinder having an intake and an outlet, the latter being in constant communication with said intake port of the power cylinder, a pump piston in said pump cylinder for drawing fuel mixture into the same and forcing it into said power cylinder when said intake and exhaust ports thereof are exposed by said power piston, a crank shaft in said crank case at the inner end of the power cylinder, a connecting rod connecting said power piston with said crank shaft, a rocker within said crank case fulcrunied between its ends on an axis parallel with said crank shaft, a link extending into 

